Is Intermittent Fasting Bad for Muscle?

The are real benefits to intermittent fasting. Even just flexibility of food choice and the freeing up of time otherwise spent on meal preparation make it worthwhile, let alone other purported claims such as life extension. But is intermittent fasting bad for muscle? Some people think so, and as proof they say there are no really big guys who fast. It seems like a reasonable observation on its surface, but it’s mistaking cause and effect.

How to Grow Muscle

There are surprisingly few ingredients in the basic recipe for muscle growth that will net you the majority of the results you’re capable of.

Weight train with a lot of effort.

Rest sufficiently.

Eat enough food to fuel muscle growth and provide the substrate to build new tissue.

Those things will provide the lion’s share of the results. Meal timing, nutrient timing, supplements, fat and carbohydrate manipulation, intra-workout food, etc—it all fades into the background, and at this stage is mostly theoretical and scientifically sketchy. Even if all the extra minutia makes any difference at all, it’s a small one.

The Biggest of the Big

But if that’s the case, what about the evidence that there are no truly big guys who fast?

The biggest, most muscular people in the world have a few things in common. First and utmost is that they have the genetic potential to accumulate huge amounts of muscle in the first place.

Next is that they typically use drugs to go beyond their already impressive natural limits.

Those two things mean they require a lot of food to support their training and growth. Often they’ll be trying to find ways to make eating more food easier, and out of practical necessity they’ll eat many large meals throughout the day.

The Essence and Uses of Intermittent Fasting

Intermittent fasting simply means not eating for a given period of time, then catching up later. When you do eat, your meals have to be larger to meet your daily caloric requirements (because you’re eating fewer times).

Fasting is a good way to help regulate food intake, and is best applied as a way to remain within limits. It’s not a way to enable maximum consumption.

This is important because it automatically means it’s not much use for anyone capable of becoming truly huge. That person needs to find a way to jam in as much food as possible, and fasting is totally unsuitable for this purpose.

It’s a Matter of Practicality

Consider professional bodybuilders—some of the largest, most muscular people in the world. It’s not unusual for these guys to need 5000 Calories per day just to maintain muscle, and to grow they often eat more (some need much more; I’ve heard of intakes above 10,000 Calories).

A common approach is to have their food spread evenly throughout the day, split into six meals. If we use 5000 Calories as the daily intake a typical professional bodybuilder needs, this means each feeding is 833 Calories—a fairly large meal, but doable. If our hypothetical bodybuilder was to use a common fasting approach—eg, skip eating during the morning, then consume calories in three afternoon/evening meals—each meal would have to be 1666 Calories. Clearly a lot less practical, especially if you’re eating a lot of stuff like veges, rice, and lean protein as many bodybuilders do.

Reverse Cause and Effect

This all means is that the only people suited to fasting are the ones who simply can’t get to that other-worldly level of muscularity in the first place. People aren’t small because they fast, they fast because they’re small. (Small being a relative term here—not to say there aren’t some very impressively muscled people who fast, just that they’re nowhere near the biggest of the big.)

So you can see the mistaken cause and effect chain. Again, it’s not the act of fasting itself that limits muscle growth, it’s just that the most heavily muscled men can’t practically do it.

Practical Takeaways

Force-feeding won’t change your genetics. If you’re not born with the genetics to grow the amounts of muscle of a professional bodybuilder or strongman, there’s nothing you can do about it. You can force-feed yourself to your heart’s content, and all that will happen is that you’ll get extremely fat (been there, done that, no thanks).

If you fall into this category you need to carefully limit how much you eat to avoid getting overly fat. Fasting is one way to help accomplish this, and is particularly useful if you like large meals (or the ability to eat some good amounts of treat food).

Fasting isn’t a method used by the most muscular men in the world, but that’s a matter of practicality, it’s not proof of detrimental effects on muscle.

Is intermittent fasting bad for muscle? No. If you decide to try it don’t worry about not being able to build muscle or losing what you have. As long as your overall calorie and protein intake is sufficient, you can safely enjoy the lifestyle. Leave the awful 15 tiny meals per day model and faulty logic to the bro-ologists in the gym.